The improvement o the flowability or flow behavior of pulverulent substances of all kinds has been the subject of many investigations and endeavors. Since the flow behavior is determined by the individual physical properties of the powders, such as, for example, the hygroscopicity, the shape and the particle size distribution of the powder particles, the capacity for accepting electrostatic charge and the adhesion of the particles to one another, very individual solutions have often been suggested for particular problems.
The addition of pyrogenic silica, that is to say a finely divided silica having a particle size of about 10 nm, is a customary and widely applicable agent for improving the flowability of powders. The attempt to improve the flowability of lamina-shaped pearlescent pigments by adding this auxiliary has, however, been unsuccessful. Lamina-shaped pearlescent pigments are, however, employed in the form of dry powder in numerous applications, and the pronounced tendency of these pigments to form agglomerates results in considerable problems in this regard. Thus, DE-A1-3,321,953, for example, suggests a modification, expensive in terms of apparatus, of bronzing machines in order to enable pearlescent pigments also to be employed in bronzing processes.